Concept:The word is reversed first, then each letter is replaced by its alphabet position and concatenated.Explanation:For PAGE: P=16, A=1, G=7, E=5.Reverse order: E,G,A,P⇒5,7,1,16.So PAGE becomes 57116.For DOWN: D=4, O=15, W=23, N=14.Reverse order: N,W,O,D⇒14,23,15,4.So DOWN becomes 1423154.Now for NEXT: N=14, E=5, X=24, T=20.Reverse order: T,X,E,N⇒20,24,5,14.Concatenate: 2024514.